Polyester-polyamides containing aziridine groups



United States Patent Ofifice 4 3,354,126 Patented Nov. 21, 1967 V 3,354,126 POLYESTER-POLYAMIDES CONTAINING AZIRIDINE GROUPS George E. Ham, Lake Jackson, and Jane E. Stevens, Austin, Tex., assignors to The Dow Chemical Company,

Midland, Mich., a corporation of Deiaware No Drawing. Filed Mar. 11, 1964, Ser. No. 351,215 13 Claims. (Cl. 260-78) This invention relates to polyester-polyamides, to such polymers containing aziridine groups, to cured resins derived from such polymers and to processes for making and curing such polymers.

The polymers containing aziridine groups are linear polyester-polyamides consisting essentially of units having the Formula I R it B N wherein R is a lower alkyl radical free of substituents reactive with the aziridine ring, R is the divalent hydrocarbon radical formed by removal of the carboxyl groups from a dicarboxylic acid, each R" is hydrogen or a lower alkyl hydrocarbon radical and n is a number having an average value of to 2. and may be different in successive polymer units. By the term lower alkyl as used herein, is meant alkyl of 1 to 4 carbon atoms.

As is evident from the above formula, the polymers consist essentially of the units shown in the second bracket, which units may optionally be randomly interspersed with up to twice as many of the units shown in the first bracket. It is also to be understood that the R" attached to the aziridine ring may or may not be the same as the R" attached directly to the back-bone chain of the polymer.

In general, the polymers of the invention having the above formula are low-melting light-colored solids are are readily soluble in many organic solvents but substantially insoluable in water. They are easily fabricated by molding or extrusion and readily form surface coatings when applied as a solution in a volatile solvent. They have the unusual and valuable property that they can be cured, i.e., crosslinked, by contact with polyfunc'tional reactants capable of opening the aziridine ring. Such reactants include polycarboxyl-ic acids and their anhydrides, diepoxides, etc. The cured resins are hard, transparent and infusible and are highly resistant to most organic solvents. A particularly useful curing agent is a copolymer of maleic anhydride which retains the acid anhydride structure, such as a copolymer with styrene. Valuable surface coatings are thus obtained when a solution of a polymer of the invention is mixed with a solution of a styrene-maleic anhydride copolymer, the solution is applied to a surface, the solvent is evaporated and the resulting film is cured by baking.

The aziridinyl polymers of the invention are conveniently made by condensing an aziridine having the Formula II NH II with a polyester-polyamide having the Formula 111 1. LL R wherein R, R, R" and n have the same significance as above. The condensation is conveniently effected by heating a mixture of the two reactants at about50-100 C. until the reaction is complete. Since the aziridine is sensitive to acids, it is essential that the ester-amide be free of acid groups. This is easily assured by the use of an excess of a tertiary'ami-ne to neutralize such groups. A volatile amine, such as triethylor tributyl-amine is preferred because of the ease of its removal from the product. Somewhat similar condensation of an aziridine with an unsaturated polyester resin have been described by Huttel et al., Farbe and Lack, 67, 71-80 (196-1) and in the copending application of M'cLen'don and Dick, Ser. No. 266,- 526, filed Mar. 20, 1963, now Patent No. 3,262,991.

The above unsaturated polyester-polyamide used in making the aziridinyl polymer are conveniently made by condensing an aziridine having the Formula IV III CHEW-CH II C wherein R, R and R" have the same significance as above. Such a condensation with a single acid anhydride, phthalic anhydride, is disclosed in British Patent 784,059. The product of the reference process, however, is useless in the present invention since it is incapable of condensing with an aziridine as described herein. The general procedure and reaction conditions useful in the process of the British patent are also useful in the present invention for making the above unsaturated polyester-polyami'des.

In making the above unsaturated polymer, maleic anhydride may be used exclusively or it may be mixed with up to about two molar equivalents of one or more other dicarboxylic acid anhydrides. Suitable such anhydrides include phthalic, succinic, adipic, sebacic and dimerized fatty acid anhydrides, and, in fact, any acid anhydride of the above formula wherein R is hydrocarbon or is free of reactive substituents.

Any aziridine having the above formula can be used to make the unsaturated polymer. The alkyl radical on the nitrogen atom may be substituted with inert groups, such as phenyl, cyano or c-arboxyalkyl.

The practice of the invention is illustrated by the following examples.

Example I perature for 4 hours. After this time the benzene was re-v moved under vacuum leaving 107.7 grams of a light. brown polymer with M.P. 5557 C.

Analysis.Calc. for C H N O percent N, 5.58. at 35-39" C. and had an infrared spectrum consistent Found: percent N, 5.01.Infrared analysis was consistent with the expected structure as shown below. The polymer with the unit structure having the Formula VI: was not readily soluble in water.

A portion of the above polymer (50.0 grams) was dissolved in 150 ml. of methyl ethyl ketone containing Malelc fifihydfldfi g 1 grams 13.3 ml. of triethyla-mine. After standing at room tem- H1914?) 0f Phthallc y q fi grams 4 perature for minutes a solution of 0.102 mole of H1016) 0f Y Y allrldllle Were dlssolved 111 ethyleni ine i 50 1, of th l h k t was dd d 30 1300 ml. of dry benzene. The 'm1xture was heated at reflux to the mixture. The mixture was then heated at reflux p r r f r 4 h r Af er rem val f he solvent temperature for 3 hours. After removal of the solvent under vaflullm there was Obtalniidg 613 grams of under vacuum there was. obtained 49.3 grams of a light d Whlch had a 0f Infrared allalysls brown solid, This polymer melted t -5 5 C, d h d of the polymer was consistent with the expected structure. an infrared spectrum consistent with that expected for 35 A Portion of the above P Y 13 was (118- a polymer having the unit tructure how b l Th solved in 60.0 ml. of acetonitrile containing 6.49 grams polymer was not readily soluble in water. of triethylamine and allowed to stand at room temperao I 0 o omoHn I-- ii-o omonm-ii-omon-ii-o CH2 CH2 N I CH; (311: C z-CH: 06115 II 06116 VII wherein n has an average val e of n ture for 30 minutes. A solution of 3.0 grams of ethyl- Example H enimine in 20 ml. of acetonitrile was then added and the m xture heated at reflux temperature for 6.5 hours. After Maleic anhydride (19.6 grams, 0.20 mole), 29.6 grams 50 removal of the solvent under reduced pressure there was (0.20 mole) of phthalic anhydride and 51.7 grams (0.40 obtained 24.1 grams of light yellow solid which melted mole) of 1-(2-acetoxyethyl)aziridine were dissolved in at 3540 C. and had an infrared spectrum consistent 1300 ml. of dry benzene and the mixture heated at reflux with that expected for the polymer unit shown below. temperature for 4 hours. After removal of the solvent The polymer was not readily soluble in Water.

l CH2 CH2 I 1 I (i711: ([3152 CHz-CH:

ON 11 ON 7 IX under vacuum there was obtained 82.7 grams of a white Example IV.--Preparation of films from above polymers solid with M.P. 3738 C. and various curing agents Analysis.Calc. for C H N O percent N, 5.60. Found: percent N, 5.62. Infrared analysis was consistent with the expected structure.

A portion of the above polymer (50.0 grams) was dissolved in 150 ml. of methyl ethyl ketonecontaining 4.1

-ml. of triethylamine. After standing at room temperature met of styrene and maleic anhydride containing 485% for 30 minutes a solution of 0.099 mole of ethylenirnine in maleic anhydride (SMA M A). The procgdure f 50 ml. of methyl ethyl ketone was added to the solution fil preparation was as f ll w and the mixture heated at reflux temperature for 3 hours. Th polymer was di o1 d i a ll amount of methyl After removal of the solvent under vacuum there Was ethyl ketone or acetonitrile. An equivalent weight of ourobtained 53.1 grams of a light yellow solid which melted ing agent based on the functional group of the curing 65 Three curing agents were used to produce hard, clear films from the above polymers. They were 2,2-bis(4- glycidyloxyphenyl) propane (DER 332), a copolymer of styrene and maleic anhydride containing 20.6 mole percent maleic anhydride (SMA 20.6% MA) and a copoly- 5 6 agent (epoxy group for DER 332 and anhydride group carbon radical formed by removal of the carboxyl groups for the SMA copolymers) per ethyleniminc group in the of a dicarboxylic acid, each R" is hydrogen or a lower P y Was dissolved in a separate small amount of alkyl radical, and n is a number having an average value methyl ethyl ketone. The solutions were rapidly miXed of to 2 and may be different in successive polymer units.

and spread on glass or bonderized steel plate. After evapo- A resin as defined in claim 1 wherein is hydro ration of the solvent at room temperature the plates were gen placed in an oven at 140 C. After curing was complete they were tested for hardness, solvent resistance and ad- A resin as defined m clalm 3 wherem R 15 hesion. The following results were obtained. The poly- Ylenemer numbers correspond to the number of the example A resin as defined 1H clalm 4 Wheflll R P describing their production. ylethyl.

Solvent Resistance Curing Pencil Polymer Curing Agent Time Hardness Acetone Ethylene H O Chloride SMA (48.5%MA)... 0.5hr.- 3H Soit- N.E NE SMA (20.6% MA)... 0.5hr.-... 3H Sol N.E Sol. DER332 2.5days.-. 3H Sol Soft N.E. DER 332 8days.-.- 5H Sol Sol Sol.

Sol.=Soluble; S0ft.=Softens; N.E.=No effect.

The films had excellent adhesion. 6. A resin as defined in claim 4 wherein R is 2-cyano- The resins having the Formula I are likewise cured by ethyl.

being heated With monomeric anhydfides 0f p y 7. A resin as defined in claim 4 wherein R is 2-acetboxylic acids, such as phthalic, maleic, succinic, glutaric OXyethyL and alkenylsuccinic anhydrides. Likewise, copolymers of g A resin as d fi d in l i 2 h i i H maleic anhydride with other vinyl monomers copolym- A resin as d fi d i l i 3 herein R is o-phenerizable therewith are useful as curing agents. Such coylelm monomers include ethylene, butadiene, acrylonitrile and 10' A resin as defined in claim 9 wherein R is acrylic acids and their esters and amides. 16th 1 Products generally similar to those described above y are obtained when 2-alkylaziridines are substituted for either or both of the aziridines .used in making those deethyl scribed above; i.e., when R" in the formulas herein repre- A resm as defined m Clam 9 wherem R sents methyl, ethyl, propyl or butyl radicals. In general oxyethyl- 11. A resin as defined in claim 9 wherein R is 2-cyanosuch 2-alkylaziridines are notably less reactive than the The Process of making the resin defined ill claim 1 unsubstituted aziridines; hence, reactions in which they Comprising fcacting y contacting atab0l1t50 t0 are used usually require longer times and/or higher tema resin Consisting essentially of units having the peratures. formula LiJTiJ We claim: wherein R is a lower alkyl radical free of substituents 1. A polyester-polyamide resin consisting essentially reactive with the aziridine ring, R is the divalent hydroof units having the formula: carbon radical formed by removal of the carboxyl groups i it i i J CH2 CHR" wherein R is a lower alkyl radical free of substituents reof a dicarboxylic acid, each R" is hydrogen or a lower active with the aziridine ring, R' is the divalent hydroalkyl radical, and n is a number having an average value carbon radical formed by removal of the caboxyl groups of 0 to 2. and may be different in successive polymer from a dicarboxylic acid, each R" is hydrogen or a lower units, with (B) about one molar equivalent, based on the alkyl radical, and n is a number having an average value Olefinic maturation in Of an aziridine having e of 0 to 2 and may be different in successive polymer formula units. 0 Hr-C HR 2. A polyester-polyamide resin consisting essentially of units having the formula:

wherein R" is as defined above.

References Cited 0 o 0 0 CHRCH,NC R' O CHRCH2N -CH=CH O UNITED STATES PATENTS J L l 2,765,294 10/1956 England 260----78 0 3,036,974 5/1962 Trieschman et al 27078 3,115,482 12/1963 Smith 26078 wherein R is a lower alkyl radical free of substituents WILLIAM SHORT Primary Examiner reactive with the aziridine ring, R is the divalent hydro- H. D. ANDERSON, Assistant Examiner. 

1. A POLYESTER-POLYAMIDE RESIN CONSISTING ESSENTIALLY OF UNITS HAVING THE FORMULA: 